# std::variant<Types...>::index

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< cpp‎ | utility‎ | variant

constexpr std::size_t index() const noexcept; |  | (since C++17)

Returns the zero-based index of the alternative that is currently held by the variant.

If the variant is `valueless_by_exception`, returns `variant_npos`.

### Example

Run this code

    #include <iostream>
    #include <string>
    #include <variant>

    int main()
    {
        std::variant<int, std::string> v = "abc";
        std::cout << "v.index = " << v.index() << '\n';
        v = {};
        std::cout << "v.index = " << v.index() << '\n';
    }

Output:

    v.index = 1
    v.index = 0

### See also

holds_alternative (C++17) | checks if a `variant` currently holds a given type (function template)
get(std::variant) (C++17) | reads the value of the variant given the index or the type (if the type is unique), throws on error (function template)

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